The objective is to study the life history from age 10 to 22 of an epidemiologically defined population of approximately 300 mentally subnormal and borderline young people in Aberdeen identified and studied in 1962. We shall examine their education and socialization, and how these were influenced by their subtype of mental subnormality, their social relationships and activities, and by the kinds and qualities of community services they received. A comparison population who are not mentally subnormal will be studied to determine the extent to which different subtypes of mental subnormality have specifically influenced the educational and socialization process. Life histories will be obtained through interviews with the subjects and their parents. A variety of existing research and administrative records will be used to cross-check, supplement and complement interview data.